Age-resisting compound for vulcanized rubber



Patented Nov. 5, 1929 UNITED STATES PATENT OFF-ICE IAX H. ZIM'JIEBMANN, F NEW'INGTON, NEW HAMPSHIRE, ASSIGNOR, BY MESNE ASSIGNMENTS, TO ALBERT C. BURRAGE, JR, 0] IPSWICH, MASSACHUSETTS AGE-BESISTING COMPOUND FOR VUioCANIZED RUDE EB 1T0 Drawing.

5 ber, especially when exposed to the atmos phere and to sunlight,-including loss of resiliency, strength and the like,are Well known and are frequently attributed to.

oxidation. Such effects obviously reduce the quality and value of the rubber and are accordingl undesirable.

Accor ingly, an object of this invention is to provide a vulcanized rubber which shall be substantially resistant to the effects of aging or oxidation. Other objects will appear from the following disclosure.

Generically, the invention includes the rovision of vulcanized rubber characterized y containing, as the age-resisting or antioxident compound, a substituted nitrosoamine, typified by the formula:

in which R and R represent alkyl or aryl radicals (or nuceli) which may be alike or unlike and may contain or be associated with one or more substituents.

In a. representative example of the invention rubber and the usual vulcanizing'andfiller materials, with or without an accelerator, and the required amount of the aging or anti-oxidant, reagent may becompounded and mixed in the usual way, as by milling, and subsequently molded and vulcanized to the desired cure, as by heating to the usual range of vulcanization temperatures.

In a typical application of the invention, under the usual vulcanizing procedure, rubber compounds were prepared as follows:

100 parts rubber 405 parts carbon 5.0 parts ZnO 3.0 parts sulphur 5.0 parts mineral rubber 3.0 parts stearic acid .8 parts mercapto benao thiazole black Application filed June 4, 1929. Serial No. 868,486.

Same as Formula I with addition of 1.0 part diphenyl nitroso-amine.

III

Same as Formula II with addition of 0.75 part diphenyl nitroso-amine.

Same as Formula I with addition of 0.50 part diphenyl nitroso-amine.

These compounds were severally mixed, as by milling in the usual manner, and then molded in thin sheets in a vulcanizing mold and vulcanized at 20 lbs. steam pressure. Samples of each compound were thus vulcamzed for periods of 30, 45, and minutes, respectively. One portion (or more) of each sample was then subjected to a tensile strength test, the results being iven in the row indicated by the letter A in the following table; and another portion was subjected to an oxygen agin test of 48 hours in an oxygen bomb at and a pressure of 300 lbs. per square inch of oxygen and then subjected to the tensile strength test the results being given in the corresponding row indicated by B in the table.

Table IContinued Table II-Continued 45 Minutes Cure Final Final F1112] Fmal t 1 stock 500,7 ensxle e 0113 0. 300% 500% ifg g 728%} pounds 300% lbs. 3101- tion rgt sq. in. percent Pressure per 08 I A 958 2420 4050 670 Aged 48 hrs. at 70 C. with 300 lbs. oxygen pressure 00 20 715 1480 1560. 510 H A 712 2000 3420 530 g3 g8 3:3 338 2 22 g2 B 1885 645 00 20 702 1520 1005 570 A 3 3 33 33 33 B 910 2200 3365 75 20 1075 2150 2520 505 Iv A 910 2500 4150 075 75 2 837 565 00 20 310 1500 430 B 935 5 2240 3340 055 90 20 1058 2490 3040 595 90 20 1100 2245 2520 550 Minutes 90 20 000 1300 1875 520 Final Table III 300% 500% 33: elqnga- $1011 A B c D I A 1105 sm kedsheets 100 1 0 100 100 Carbon black 40 0 40 B 1050 2180 2660 \605 Mineral rubber 5 5 5 5 n A 035 2050 4150 050 gfigfififf- 5 3 3 3 Stearic ac1d.. 3 3 3 3 B 972 2380 3455 655 11\)/Ier0apt0 blenfiolthrazolm 8 $5 8 8 ibeta nap t y ni rem-amine" In A 11.35 4175 635 Phenylbetanaphthylnitr0s0-amine 0 0 0.75 0 5 B 1220 2600 3330 620 Phenyl alpha naphthyl n1troso-am1ne-- 0 0 0 0. 7

IV A 1120 2030 4280 025 C ul'e B 1120 2520 3280 015 $33 fi gg Stock Pounds 300% 500% lbs. per tlon in Min. pressure sq. in. per cent S1m1lar vulcanlzmg experlments were carrled out wlth rubber c0mp0s1t1011s contalnlng 60 2 33 3 $2 23 2 338 60 000 other mtrose ammes, lncludlng both 11ke and 60 1 762 2100 3700 700 unhke subst1tuents and hydrocarbon radlcals 60 20 667 1905 3200 655 of both the aliphatic and aromatlc serles. 75 g 321 1 2223 2% 700 5 050 The expenmental results thus obtalned are 75 20 900 3 5 384 5 presented 1n the followmg tables: 75 655 5 Table II 20 20 955 2000 4000 055 90 20 970 2530 ,4000 555 A B o D Aged 48 hrs. at C with 300 lbs. oxygen pressure (slmggredgleits 128 12g 12g 21' 0B 3C Mineral tubber 5 5 5 6O 20 640 1450 1725 545 Zinc oxide 5 5 1 5 60 20 896 2080 2965 630 ulphm- 3 3 3 60 20 810 1955 2880 650 iiearic acid 8 3 8 g 60 20 765 1880 2760 640 ercapto benzo t iazo e t Phenylbetanaphthylnitroso-amine. 0 0. 0 75 20 6 1530 1630 510 genzyl ghergyl nitroso-amine 8 g i g g gs arbazo m roso-amme 75 20 883 2140 3120 M0 00 20 30s 1520 450 Cure Final 00 20 1045 2300 3130 030 tensile 9o 20 995' 2275 3035 005 Stock 300% 500% lbs per 90 20 1030 2300 3030 015 Mm Pounds s in pressure Table IV 00 20 740 2010 3335 550 1 50 20 737 2110 3535 555 A B C D 50 20 321 2200 3720 570 00 20 700 2020 3450 030 Smoked sheets 100 100 100 100 75 20 843' 2250 3660 670 Carbon black. 40 40 40 40 75 20 880 2390 3910 665 Mineral rubber 5 5 5 5 75 20 985 2000 4200 705' Zmc oxide... 5 5 5 5 75 20 850 2280 3700 300 Sulphur--. 3 3 3 3 Stearic 301d. 3 3 3 '3 90 20 930 2460 3890 600 Mereapto benzo thlazole- 0. 8 0.8 0. B 0 8 90 20 990 2600 3950 630 Diethy1nitroso-amine. 0 0. 75 0 0 90 20 1068 2720 4110 640 Piperidine-nitrosmaminm" 0 0 0. 75 0 90 20 900 2580 3950 650 Methyl-phenyl-nitroso-amine 0 0 0 0. 75

Table IVCont1nued From the data thus obtained, it is clear that the vulcanized products containing a substi- Cure mm tuted nltroso-amlne exh1b1t a greatly 1msm 300% 500% c sne 515118 1- proved reslstanoe to agmg or oxldation as 5 5 22 2 $1 1,3 1nd1cated by the oxygen bombtreatment, both 70 wlth respect to mtermechate and final elon- 60 675 1870 3350 690 gatlon values, than the products to wh1ch 50 g 3 g 2% 015 such addltlon has not been made. 0 Q 20 712 m0 3370 g It 1s also shown that d1aryl subst1tuted ni-v 75 m m 2120 3630 680 troso-amlnes are espec1al ly eflectlve 1n th1s 75 g 3 1 13 respect, wh1le those contalnmg an alkyl sub- 75 20 m 5490 3940 655 stltuent Instead of an aryl substltuent, are 90 m m 2440 3970 am somewhat less eflectlve, and wlth those 1n 00 20 002 2010 5010 540 wluoh both ar 1 subst1tuents are re laced 90 20 1168 2900 4160 630 1 y 9o 20 .1120 2825 m0 630 by alkyl rad1ca ls, the ant1-ox1dant or age-re- 80 slstlng propertles are st1ll lower. Aged 4511111; at 10 0 with 300155. oxygen pressure Other compounds, whlch'are related to the substltuent nltroso-ammes above defined and 00 20 13 211 have been thus treated 1n accordance w1th the $2 1570 3 580 mventlon, lnclude carbazole, nltroso-amlne 20 788 Wl'llCl'l may be spoken of as mt-roso-N' carba- 15 20 800 1886 2110 v540 zole, 15 20 ans 1055 2245 510 15 20 10:10 2140 2300 550 15 20 1000 2100 2100 550 Table v p This compound is not strictly in the same 30 category w1th the other compounds tested,

' A y B G D and'shows but very httle 1mprovement 1n the aglng properties of rubber products con- Smokedsheets 100 1 100 talnlng 1t. The results are g1ven, however,

g g g because It 1s related to the other mtrosog g g g compounds. Its failure to be efii'ectlve may 100 s a :1 a be attrlbuted to the valance llnkage between 8- 8:? 8- 8' groups correspondlng to the R and R groups p g g 3- .3 75 of the mtroso-amme WhlCh W111 be apparent from the formula above g1ven. 40 Wh1le' the above dlsclosure relates to pre- 10:;

1111 1 1511151 ferred mstances of the apphcation of the 111- Stock P d5 5, 2,83%; ventlon and to speclfic re-agents employed 1n r ure f speclfic proport1ons, 1t 1s to be understood that var1at1ons may be made thereln and 1n 50 20 85B 2250 2000 1 the nature and amount of the several re- 3 3,13 3% 23 660 7 agents used, accordlng to the particular re- 20 845 qulrements of the roduct, as W111 be clear ,15 20 025 2100 3015 055 to those sk1lled'1n t e art of treatlng rubber.

75 20 832 2360 3820 660 I 1 Y 75 20 975 2420 41110 070 0 8 m 75 A rubber product whlch has been vuloan- 1'15 00 20 1040 2500 412 675 lzed 1n the presence of d1-phenyl mtroso- 00 20 1050 2550 4000 055 90 Z) H30 2720 4010 64 111111118. 7 3 blgned by me at Boston, Massachusetts,

A v th1s 24th day of May, 1929. y 55 MAX H. ZIMMERMANN. 

